Related Clues:
- Side of a Cartesian quadrant
- It often represents time
- Line on which y = 0
- Horizontal line
- Place for Cartesian coordinates
- Graph of y = 0
- Vertical graph line
- Graph basis
- Base line
- Y = 0 line
- Horizontal reference line on a graph
- Line up for the mathematicians?
- Vertical reference line on a graph
- Graph reference line
- Graph mainstay